improved default network interface

lib/index.js

@@ -80,6 +80,7 @@
 // --------------------------------
 //
 // version	date	comment
+// 3.4.2  2016-09-01  improved default network interface
 // 3.4.1  2016-08-30  updated docs
 // 3.4.0  2016-08-30  rewritten current process cpu usage (linux)
 // 3.3.0  2016-08-24  added process list
@@ -115,6 +116,7 @@
 
 const os = require('os')
   , exec = require('child_process').exec
+  , execSync = require('child_process').execSync
   , fs = require('fs')
   , lib_version = require('../package.json').version;
 
@@ -1162,23 +1164,51 @@ exports.disksIO = disksIO;
 // 8. Network
 // ----------------------------------------------------------------------------------
 
-function getFirstExternalNetworkInterface() {
+function getDefaultNetworkInterface() {
 
   let ifacename = '';
-  let ifaces = os.networkInterfaces();
+  let cmd = (_linux ? "route | grep default | awk '{print $8}'" : "route get 0.0.0.0  2>/dev/null | grep interface: | awk '{print $2}'");
+  let result = execSync(cmd);
+  ifacename = result.toString().split('\n')[0];
 
-  for (let dev in ifaces) {
-    if (ifaces.hasOwnProperty(dev)) {
-      ifaces[dev].forEach(function (details) {
-        if (details && details.internal == false) {
-          ifacename = ifacename || dev;
-        }
-      })
+  if (!ifacename) {         // fallback - "first" external interface
+    const sortObject = o => Object.keys(o).sort().reduce((r, k) => (r[k] = o[k], r), {});
+
+    let ifaces = sortObject(os.networkInterfaces());
+
+    for (let dev in ifaces) {
+      if (ifaces.hasOwnProperty(dev)) {
+        ifaces[dev].forEach(function (details) {
+          if (details && details.internal == false) {
+            ifacename = ifacename || dev;
+          }
+        })
+      }
     }
   }
+  if (ifacename) _default_iface = ifacename;
   return ifacename;
 }
 
+function networkInterfaceDefault(callback) {
+
+  return new Promise((resolve, reject) => {
+    process.nextTick(() => {
+      if (_windows) {
+        let error = new Error(NOT_SUPPORTED);
+        if (callback) { callback(NOT_SUPPORTED) }
+        reject(error);
+      }
+
+      let result = getDefaultNetworkInterface();
+      if (callback) { callback(result) }
+      resolve(result);
+    });
+  });
+}
+
+exports.networkInterfaceDefault = networkInterfaceDefault;
+
 // --------------------------
 // NET - interfaces
 
@@ -1258,7 +1288,7 @@ function networkStats(iface, callback) {
         reject(error);
       }
 
-      _default_iface = _default_iface || getFirstExternalNetworkInterface();
+      _default_iface = _default_iface || getDefaultNetworkInterface();
       iface = iface || _default_iface; // (_darwin ? 'en0' : 'eth0');
 
       let result = {
@@ -2647,7 +2677,7 @@ function getDynamicData(srv, iface, callback) {
         reject(error);
       }
 
-      iface = iface || getFirstExternalNetworkInterface();
+      iface = iface || getDefaultNetworkInterface();
       srv = srv || '';
 
       // use closure to track ƒ completion